Why is it worth combining a PV farm with an energy storage system?
From a technical point of view, an energy storage system at a PV farm acts as a buffer that collects excess energy produced during the day and releases it when market demand rises – for example, in the evening. This translates into higher energy selling prices and thus increases the investor’s revenues.
Storage systems also make it possible to increase the level of self-consumption of energy within a single installation or energy cluster. In practice, this means less dependence on external power suppliers and reduced costs of purchasing energy from the grid. Importantly, a system integrated with storage more easily meets connection conditions and technical requirements of distribution network operators, which facilitates the process of obtaining permits and technical approvals.
From a financial perspective, an energy storage system is a way to increase profitability, but also a hedge against energy price volatility and the risk of the operator not accepting surpluses. For investors, this means short-term profits as well as greater economic resilience of the installation to legislative and tariff changes.
What to consider before integration?
Before integrating a photovoltaic farm with an energy storage system, it is necessary to conduct a thorough technical assessment of the existing installation. In many cases, upgrading older PV systems may be unprofitable or technically limited. Problems may include insufficient connection capacity, incompatible inverters, or limited space for storage components.
That’s why, at the profitability assessment stage, it’s important to analyze the cost of adapting the existing infrastructure versus designing a PV system with storage from scratch. A new installation project that includes battery storage at the technological concept stage allows cost optimization and avoids difficult technical compromises. In the case of modernization, it is advisable to carry out a technical audit that will clearly indicate whether integration is feasible without excessive investment outlays.
How to choose the right energy storage system?
Selecting the right storage system requires knowledge of available technologies, as well as a precise analysis of production and demand profiles. The most commonly used are lithium-ion batteries, which offer high energy density, high efficiency, and relatively long life cycles. For projects requiring high capacity with lower operating intensity, flow batteries may also be used – characterized by scalability and operational safety.
It is essential to properly match the power (in kW) and capacity (in kWh) of the storage system. Underestimating capacity can lead to quick overfilling or shortages during peak demand, while oversizing generates unnecessary investment costs. Profitability calculations should also consider projected energy prices, tariff structures, investor needs regarding self-consumption, and connection requirements. Cooperation with an experienced EPC (engineering, procurement, construction) integrator is often a beneficial solution, as they can design a storage system precisely tailored to the characteristics of a given farm.
What does the technical integration process look like?
The technical integration of a PV installation with an energy storage system mainly involves connecting both systems in a way that ensures safe and efficient operation. In practice, two main variants are possible: connection on the AC side (alternating current) or on the DC side (direct current).
- The AC variant assumes that both the PV system and the storage are connected to a common point on the AC side – usually the same transformer or busbar. This solution is more universal and easier to implement in upgraded installations.
- Integration on the DC side enables higher energy efficiency and lower conversion losses but requires the use of specialized bidirectional inverters and is more difficult to implement in older systems.
An essential part of integration is also the selection of appropriate protection devices, disconnection systems, surge protection, and temperature control systems. The entire system architecture should be designed in accordance with applicable technical standards, and the technical documentation must be approved by the distribution system operator.
Control and energy management – the role of SCADA systems
Modern energy storage systems cannot function as passive infrastructure components. Their full utilization requires the use of advanced control and energy management systems – particularly SCADA (Supervisory Control and Data Acquisition).
This system allows real-time monitoring of the storage state, management of charging and discharging cycles, and integration with the PV farm’s production profile. It also enables demand and price forecasting, optimization of self-consumption, and response to market price signals. Moreover, advanced predictive algorithms can support decisions on when to store energy and when to sell it to the grid.
Integration of SCADA with a photovoltaic installation increases the overall system efficiency and also allows for reporting required by the Energy Regulatory Office (URE) and grid operators.
The most common mistakes in integration design
Despite the market’s growing experience in combining PV farms with energy storage systems, typical design errors still occur.
- The first is improper estimation of the energy production profile in relation to the storage system’s operating cycles. Too little battery capacity prevents full utilization of its potential, while too large increases investment costs without proportional benefits.
- The second common issue is hardware incompatibility between PV inverters and the energy storage system – especially in modernization projects where parts of the infrastructure come from earlier investment stages. There is often also insufficient preparation regarding grid requirements – for example, in terms of power quality parameters or the storage system’s ability to operate in island mode.
- The third problem is neglecting control system integration. The lack of a coherent EMS solution leads to suboptimal charging and discharging cycles, resulting in reduced yield and higher operating costs.
- Another mistake is designing an installation with storage without prior consultation with the grid operator, which can lead to delays in connection or the need for costly reconstruction of connection infrastructure.
- Finally, investors often overlook the aspects of maintenance and storage system lifespan. The lack of a technical maintenance plan and TCO (Total Cost of Ownership) analysis leads to unforeseen operational costs in later years.
Integrating a photovoltaic farm with an energy storage system is a decision that can significantly improve the profitability and stability of the entire investment, provided it is preceded by technical analysis, appropriate technology selection, and professional system design. It is essential to consider equipment compatibility, operational needs, and connection possibilities. A properly designed integration increases energy independence, facilitates compliance with grid requirements, and opens access to additional revenue streams such as system services.
Frequently asked questions (FAQ)
1. Is it worth combining a PV farm with an energy storage system?
Yes. It increases investment profitability, reduces transmission losses, and improves operational flexibility.
2. What energy storage technologies are most commonly used?
Lithium-ion batteries dominate, although flow batteries are also used in large-scale projects.
3. Can an energy storage system be integrated with an existing PV farm?
Yes, but it requires a technical analysis. Sometimes, building a new system from scratch is more cost-effective.
4. What are the main variants of technical integration?
Systems can be connected on the AC side (easier implementation) or DC side (higher efficiency but greater technical requirements).
5. What are the most common design mistakes?
Incorrectly selected storage capacity, hardware incompatibility, lack of control system integration, and failure to consult with the grid operator.
6. Is approval from the grid operator required?
Yes. The connection conditions must include both the PV installation and the energy storage system.
7. What are the benefits of using a SCADA system?
It enables optimal energy management, operation monitoring, and compliance with URE and DSO reporting requirements.
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